Economic decline by some of the U.S.’s closest allies and the subsequent decline in their military power “now poses considerable challenges for U.S. strategy,” says a new report from the nonpartisan Center for Strategic and Budgetary Assessments.

“In the event conflict occurs, the United States will face even greater challenges in defending its increasingly overmatched allies in these regions. U.S. allies are likewise becoming less capable of making meaningful contributions to the expeditionary military operations that have figured centrally in U.S. policy during the post-Cold War period,” says the report written by Hal Brands, a senior fellow at the policy group who was a special assistant to then-Defense Secretary Ash Carter.

The report, “Dealing With Allies in Decline: Alliance Management and U.S. Strategy in an Era of Global Power Shifts,” says the economic and military power of rivals such as Russia and China has increased while that of U.S. partners has slipped over the past two decades.

U.S. allies are “becoming less capable of making meaningful contributions to the expeditionary military operations that have figured centrally in U.S. policy during the post-Cold War period. Additionally, allied decline is eroding the broader global influence that U.S. allies can bring to bear and weakening the hard-power backbone of the liberal global order,” Brands writes.

The report can be downloaded here: http://csbaonline.org/uploads/documents/ALLIES_in_DECLINE_FINAL_b.pdf